Method of treating steel bars



April 22, 1941. J. w. LEIGHTON IETHOD OF TREATING STEEL BARS Filed Dow, 23, 1938 IN VEN TOR A TTORNE Ki yiiolz Z' Y H1 VAZQQ.

Patented Apr. 22, 1941 METHOD OF TREATING STEEL BARS John W. Leighton, Port Huron, Mich. Application December 23, 1938, Serial No. 247,377

2 Claims.

The invention relates generally to metal working and it has particular relation to machinable steel bars and a method of manufacturing such bars.

It may generally be stated that it is well known in the art of metal working to provide hot rolled steel bars of different cross-sectional shapes for use in connection with various metal working machines such. for example, as automatic screw machines. With respect to the latter type of machine in particular, it will be understood that as a rule, the bars used are oi considerable length and are progressively fed through the machine. It is of importance that the sectional dimensions of the bar be held to fairly close tolerances to avoid interference with the operation of the machine and it is also important that the suriace of the bar be fairly smooth. The cost of providing such bars for this purpose naturally is a very important factor and when it is considered that there is an enormous use of steel bars of this general character and for the purposes mentioned. any reduction in cost of manufacturing the bars becomes a highly important item.

In so far as is known, the usual practice involved in manufacturing bars of the type mentloned requires either cold drawing or cold rolling of hot rolled bars produced in the steel mill wherein in either case, the hot rolled bar is cleaned of scale by treating it with a pickling solution and in connection with the drawing process, the bar also is coated with lime. Pickling oi the hot rolled bar to remove the scale, and liming ii effected, involves a substantial expense item. Subsequent cold rolling by passing the bar repeatedly between rollers until the desired size is obtained, requires considerable time and, therefore, is likewise expensive.

Urdinarily, in the use of either of these processes, hot rolled bars are purchased which have been pickled to remove the scale and if such hers are not used within a short time, the surface metal hegins to rust.

line oiaject of the present invention is to provide improved process for manufacturing rrlachirrahie steel bars such as generally indicated, whlclrr requires fewer operations and less time, results in superior product uniform and ength, which provides a .nich in general involves object oi the invention provide L...,. rcved such alcove indicated machines may he used for this purpose.

which will allow storage of hot rolled bars in a manufacturing plant without removing scale therefrom until immediately before finishing the bars for use in automatic screw machines and the like.

Other objects of the invention will become apparent from the following specification and from the claims hereinafter set forth.

For a. better understanding of the invention, reference may be had to the accompanying drawing illustrating generally the manner in which the invention is employed and wherein:

Figure 1 illustrates more or less diagrammatically one ste in the process embodied in the present invention;

Fig. 2 illustrates another step involved in such process;

Fig. 3 is a fragmentary view in cross-section of the bar at one stage of its manufacture and as seein substantially along the line 3-3 of Fig.

an 5t812g. 4 its a similar view of the bar at another an as seen substantial] l n 4-4 of Fig. 1; and y a o g the line Fig. 5 is a View of the finished bar as seen suhstantially along the line 5-5 of Fig. 2. I

Referring to Fig. 1, a hot-rolled bar, as it oppears with the scale remaining thereon, is shown at ill at the entry side of the apparatus. ill be understood that the cross-sectional all alone of the bar in this condition are all grcater than the crosssectional dimensio the finished bar to he obtained. Proceeding the present process, the bar 8 first passes through a shot blasting machine indicated at M and at the same time it is rotated so that the scale is subjected to forces which eiiiciently act to remove the scale.

It is to be understood that this machine forcefully throws large numbers of small, hard steel shot against the surfaces of the bar and different The machine it is rather diagrammatically illustrated and includes a drum l3 having a plurality of nozzles it through which the shots are directed against the surface of the bar.

For rotating the bar While at the some supporting it for movement through the blasting machine, pinions l5 and it may he ployed which have hexagonal openings at center through which the hexagonal. These pinions are journaled in hearing so and that are anchored on a static (not shown). isultahle means ma,

, tion of drawing and extruding forces.

provided for turning the pinions I5 and Hi together and thus rotating the bar, and a push rod 22 has been illustrated as the means for pushing the bar through the pinions and 'drum although if desired, rollers may be employed for this purpose and such rollers may be disposed at the inlet and discharge side of the apparatus.

Figure 3 illustrates the bar as it is delivered to the machine H and at this stage the surfaces of the bar are covered with scale, indicated generally at 24. This scale, as indicated previously, results from the hot-rolling processes employed in the steel mill during the initial manufacture of the bar from steel ingots. The bar, in passing through the shot blasting machine, is freed from this scale and an important feature of the present invention ,is that in directing the shot forcefully against the surfaces of the bar. numerous very small recesses or pits are formed in the surfaces and the bar in this condition is shown by Figure 4. Such pits or recesses are very shallow, small in width, and are closely arranged. It will be understood that they are not regularly arranged as one pit will overlap another pit in many instances. but the general appearance is that of .a pitted formation wherein the pits are extremely numerous. small. and close together.

It will be appreciated that removal of the scale by the shot blasting step in the process is inexpensive and that it may be effected quickly.

Moreover. it can be readily effected at any time and the bar. as it leaves the shot blasting machine. is ready for further use without delay. Rust and scale are removed immediately before any further steps in the process and this is distinctly advantageous since avoided.

The pitted bar now is passed through a die 30 having a conical entry 3| and a reducing portion 32 which acts to reduce the diameter of the bar to that desired and to provide a very smooth surface. An annular groove 34 is provided in. the entry 3| and communicates with alubricant line 35. Lubricant is conducted to the, surfaces of subsequent rusting is the. bar just before it enters the reducing portion 32 and this lubricant flows over the pitted surfaces and lodges in the pits or recesses. In this manner, the lubricant is carried into themducing portion 32, from which it follows that during reduction of the diameter the surfaces of the bar efficiently are lubricated and this is very important if the reducing action is to be practical.

The bar may be initially pushed through the die 30 by means of a pushing collet 31 that grips the surfaces of the bar and after the bar passes sufficiently beyond the discharge end of the die. one or more additional collets or jaws devices may be employed for drawing the bar through the die. By using collets at both sides of the die, the bar may be extruded or it may be drawn or it may be moved through the die by a combina- The advantage of the extruding process is that there is less tendency for variation in the diameter of the bar due to the fact that the finished construction is not subjected to tensile forces although usually the tension forces required do not reduce the dimensions beyond permissible tolerances.

The process permits bringing hot-rolled bars with scale thereon into the manufacturing plant V and little time is required in passing one of the bars through the shot blasting apparatus and in removing this bar to the reducing apparatus and reducing its dimensions to those desired. Fewer operations are thus required in handling the bar and the expenses of conditioning it are reduced very substantially. This reduction in expense necessarily is reflected in a lower cost in screwthreaded products produced from the bar and when it is considered that enormous quantities of screw threaded products are produced from bars,

the total benefit derived from this process, particularly in the way of a reduction in cost, becomes a most important item.

Although only one form of the invention has been described and illustrated in detail, it will be apparent to those skilled in the art that various modifications may be made without departing from the scope of the appended claims.

What is claimed is:

l. The method of treating steel stock to obtain an elongated bar of accurate and uniform crosssectional dimensions and in condition to be delivered or fed to a metal working machine such as an automatic screw machine, which comprises providing an elongated bar of rolled steel slightly larger in cross-section than the finished bar to be obtained, forcefully directing small solid particles against the surface of the bar to remove scale and also to form closely related, small recesses or pits in such surface adapted to retain a lubricant, applying fluid lubricant to the pitted surface immediately adjacent to a reducing die in such manner that the lubricant will be held in the pits as they enter the die, and forcing the bar through the die with the pits retaining the lubricant to reduce the sectional size of the bar to a smaller size uniform and accurate throughout the length of the bar and to eliminate the pits or recesses and provide a smooth surface.

2. The mehod of treating steel stock to obtain an elongated bar of accurate and uniform crosssectional dimensions and in condition to be de livered or fed to a metal working machine such as an automatic screw machine, which comprises providing an elongated bar of rolled steel slightly larger in cross-section than the finished bar to be obtained, moving the bar in the direction of its length, forcefully directing small solid particles against the surface of the bar as it is moved so as to remove scale from such surface and to form closely related small recesses or pits in such surface that are adapted to hold lubricant, applying fluid lubricant to the pitted surface during continued movement of the bar and at a point immediately adjacent to a reducing die in such manner that the lubricant will be held in the pits as they enter the die, and forcing the bar through the die with the pits retaining the lubricant to reduce the sectional size of the bar to a smaller size uniform and accurate throughout the length of the bar and to eliminate the p1ts or recesses and provide a smooth surface.

JOHN W. LEIGHTON. 

